<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

</body>
<script>
  let emperor = {
    prince: ['prince1', 'prince2', 'prince3'],
    princess: ['princess1', 'princess2', 'princess3']
  }

  const prince = Symbol('bastard')
  emperor[prince] = 'bastard'

  console.log(emperor)
</script>

</html>